We use computers in the PC-104 form factor, with most of the cards manufactured by Diamond.

They are pretty much the smallest ones you can get that are built specifically for the types of things we need them for, like making PWM signals, reading analog channels, setting digital and relay outputs, etc.

We are using 2 Arduino's linked together for our ground test setup, running valves/solenoids etc.Cheapest way for us to get set up doing this kinda stuff, not sure if its the easiest, I'd have to ask David, my man programming it all!!!

It's all about requirements guys. If you need simple PWM/DAC/ADC stuff, use an Atmel device like this one: http://www.atmel.com/dyn/resources/prod ... /8159S.pdf The development environments are less than the cost of a PC and the devices are really cheap. I've run a 200Hz PID controller on an older version of this device (tho I did have to hard-code some of the floating point constant math to make it fast enough).

"We can lick gravity, but the paperwork is overwhelming" -- Werner Von Braun"It's all fun and games until the potato chips get loose." (said of the ISS by Gizmodo on space.com)"A journey of a thousand miles begins with a single step. A journey of a hundred thousand miles begins with lots of flames, noise and smoke!" -- Emory Stagmer

All for $50 US. I have 2 and will be using them as part of a standard motor test "kit" that I will be marketing for small engines--small enough for the tabletop kit. I will be testing it wearing goggles, right in front of me, like I were testing a model plane engine, which, in a sense, this is.

The 1st engine to be built, tested will be for Stage-3, because its performance so strongly affects the total rocket size. By measuring flow rate and pressure I intend to find C*, from which vacuum Isp can be predicted to within a few %. Looking for 1550 or more m/sec on propane/LOX, for Isp over 250. 1700 is reasonable expectancy for Isp closer to 300.

The engine is to have a vacuum thrust of about 15N, and weigh less than 75 grams, including the TVC servos. 2nd stage engine is to be about ten times that--still in the "tabletop" size.

Microlaunchers is still searching for interested participants for the entry, and a production run of about 100 vehicles, to be marked for 125 gram "Pocket Cube" launchers. I don't expect to find any here, but if seriously interested, I can be reached at the ML email address.